On Wed, May 18, 2022 at 01:08:31PM -0700, Tom Rix wrote:
>
> On 5/17/22 11:48 PM, tien.sung.ang@xxxxxxxxx wrote:
> > From: Ang Tien Sung <tien.sung.ang@xxxxxxxxx>
> >
> > To support the error handling of a truncated bitstream sent.
> > The current AIB CvP firmware is not capable of handling a
> > data stream smaller than 4096bytes. The firmware's limitation
> > causes a hung-up as it's DMA engine waits forever for the
> > completion of the instructed 4096bytes.
> > To resolve this design limitation, both firmware and CvP
> > driver made several changes. At the CvP driver, we just
> > have to ensure that anything lesser than 4096bytes are
> > padded with extra bytes. The CvP will then, initiate the
> > tear-down by clearing the START_XFER and CVP_CONFIG bits.
> > We should also check for CVP_ERROR during the CvP completion.
> > A send_buf which is always 4096bytes is used to copy the
> > data during every transaction.
> >
> > Signed-off-by: Ang Tien Sung <tien.sung.ang@xxxxxxxxx>
> > ---
> > drivers/fpga/altera-cvp.c | 24 +++++++++++++++++++-----
> > 1 file changed, 19 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/fpga/altera-cvp.c b/drivers/fpga/altera-cvp.c
> > index 4ffb9da537d8..80edcfb5e5fc 100644
> > --- a/drivers/fpga/altera-cvp.c
> > +++ b/drivers/fpga/altera-cvp.c
> > @@ -81,6 +81,7 @@ struct altera_cvp_conf {
> > u8 numclks;
> > u32 sent_packets;
> > u32 vsec_offset;
> > + u8 *send_buf;
>
> Why is it necessary to hold the send_buf in this structure ?
>
> If it is used only in *_write, could it alloc/freed there ?
>
> Because the write happens rarely, my preference is to alloc/free in
> *_write().
Is it better alloc in write_init()?
Thanks,
Yilun
>
> > const struct cvp_priv *priv;
> > };
> > @@ -453,7 +454,11 @@ static int altera_cvp_write(struct fpga_manager *mgr, const char *buf,
> > }
> > len = min(conf->priv->block_size, remaining);
> > - altera_cvp_send_block(conf, data, len);
> > + /* Copy the requested host data into the transmit buffer */
> > +
> > + memcpy(conf->send_buf, data, len);
> Is a memset needed for a short buffer ?
> > + altera_cvp_send_block(conf, (const u32 *)conf->send_buf,
> > + conf->priv->block_size);
> > data += len / sizeof(u32);
> > done += len;
> > remaining -= len;
> > @@ -492,10 +497,13 @@ static int altera_cvp_write_complete(struct fpga_manager *mgr,
> > if (ret)
> > return ret;
> > - /* STEP 16 - check CVP_CONFIG_ERROR_LATCHED bit */
> > - altera_read_config_dword(conf, VSE_UNCOR_ERR_STATUS, &val);
> > - if (val & VSE_UNCOR_ERR_CVP_CFG_ERR) {
> > - dev_err(&mgr->dev, "detected CVP_CONFIG_ERROR_LATCHED!\n");
> > + /*
> > + * STEP 16 - If bitstream error (truncated/miss-matched),
> > + * we shall exit here.
> > + */
> > + ret = altera_read_config_dword(conf, VSE_CVP_STATUS, &val);
> Should this be STEP 17 ? the old 16 checked something else.
>
> Tom
>
> > + if (ret || (val & VSE_CVP_STATUS_CFG_ERR)) {
> > + dev_err(&mgr->dev, "CVP_CONFIG_ERROR!\n");
> > return -EPROTO;
> > }
> > @@ -661,6 +669,12 @@ static int altera_cvp_probe(struct pci_dev *pdev,
> > pci_set_drvdata(pdev, mgr);
> > + /* Allocate the 4096 block size transmit buffer */
> > + conf->send_buf = devm_kzalloc(&pdev->dev, conf->priv->block_size, GFP_KERNEL);
> > + if (!conf->send_buf) {
> > + ret = -ENOMEM;
> > + goto err_unmap;
> > + }
> > return 0;
> > err_unmap:
